1. Field of the Invention
The present invention relates to a generating apparatus of such pulse signal as corresponding to the building up phase of the rectangular wave signal generated by opening and closing of a mechanical contact, particularly to a pulse generating apparatus having a prevention circuit for erroneous function by chattering, improper contact, etc., at the time of opening and closing of a contact.
2. Description of the Prior Art
An apparatus to generate such pulse signal as corresponding to a rotating speed of a rotating machine by opening and closing a mechanical contact with rotation of the machine to put the current ON or OFF, and to control the rotation of other rotating machines to secure synchronism is generally used as, for example, a synchronizing equipment between a magnetic reproducing machine and a cine-projector, and between a magnetic sound recording equipment and a cine-camera, etc. In such apparatus employing the opening and closing of a mechanical contact, unnecessary pulse may be generated by chattering, improper contact, etc. which take place in opening and closing the contact, and erroneous functioning may be caused thereby, which need to be prevented. That is, when the rectangular wave output generated by opening and closing of a contact is differentiated by a differentiation circuit to make it pulse signal, as it becomes rectangular wave signal accompanying short pulse at the time of opening and closing by chattering, etc. of the contact, if it is simply differentiated to take out such pulse signal as corresponding to the building up phase, false pulse is mixed into normal driving pulse, thereby causing erroneous action in control of the equipment being controlled.